Analysis of the fluctuations of a single-tethered, quantum-dot labeled DNA molecule in shear flow

A novel technique for analyzing the conformational fluctuations of a single, surface-tethered DNA molecule by fluorescence microscopy is reported. Attaching a nanometer-sized fluorescent quantum dot to the free end of a λ-phage DNA molecule allows us to study the fluctuations of a native DNA molecule without the mechanical properties being altered by fluorescent dye staining. We report on the investigation of single-tethered DNA in both the unperturbed and the shear flow induced stretched state. The dependence of the observed fractional extension and the magnitude of fluctuations on the shear rate can be qualitatively interpreted by Brochard's stem-and-flower model. The cyclic dynamics of a DNA molecule is directly observed in the shear flow experiment.

Revisiting Parkinson: After six decades, his triangle remains useful

Background:

The welcome advent and subsequent development of interventional neuroradiology led to an important paradigm shift in the management of many cerebrovascular diseases. This paradigm shift is especially true for carotid cavernous fistula and, for some time now, endovascular techniques are the mainstay approach for these lesions. The neurosurgical intervention should be adopted when the endovascular treatment is not practicable.

Case Description:

We present the surgical solution adopted to treat a patient with an indirect carotid cavernous fistula (CCF), with quickly progressive symptoms, in which it was not possible to treat using the currently standardized endovascular technique. A pretemporal craniotomy with peeling of the dura mater at the middle fossa and exposure of Parkinson’s triangle on the lateral wall of the cavernous sinus was performed. Fibrin glue was injected by puncture of the lateral wall of the cavernous sinus for direct thrombosis of this sinus and the superior ophthalmic vein.

Conclusion:

In the now far 60s, Parkinson already treated patients with CCF effectively and elegantly through the lateral wall of the cavernous sinus. Revisiting techniques from the past, associating them with the supplies widely available today, can sometimes be the solution to some especially challenging cases that we face in our profession.

Surgical treatment of spinal arachnoid web: Report of two cases and literature review

BACKGROUND

Arachnoid webs (AWs) can cause cord compression and syringomyelia in the thoracic spine. Here, we describe two patients who underwent operative treatment for AW and reviewed the literature.

CASE DESCRIPTION

Two patients underwent surgical treatment for thoracic AW. Both presented with spastic gait and numbness in the lower extremities. On MR, these lesions exhibited the "scalpel" sign (i.e. due to the accumulation of cerebrospinal fluid on the dorsal aspect of the spinal cord). Operative intervention, consisting of fenestration and web resection, resulted in symptom resolution.

CONCLUSION

Thoracic AWs are rare lesions that should be considered among the differential diagnosis of spinal compressive syndromes. Surgical fenestration and resection of the AW correct the flow dynamics allowing for full symptoms resolution.

Field H1 of Forel vs Subthalamic Nucleus Electrical Stimulation in Parkinson's Disease: Long-term Effects on Motor Symptoms and Quality of Life

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) relieves motor symptoms, including levodopa-responsive gait disorders in Parkinson's disease (PD). Traditionally, STN-DBS is not indicated to treat severe, clinically resistant axial symptoms. In this scenario, field H1 of Forel (FF) stimulation (FF-DBS) is likely a feasible option, given it improves motor symptoms, including freezing of gait (FOG), as shown by a short-term study. However, no data are available about the long-term effects of this therapy. Finally, no study has compared the long-term effects of FF and STN-DBS.

OBJECTIVE

We report the long-term outcome (>five years) of bilateral FF-DBS in patients with PD. We also compare the effects of FF-DBS and STN-DBS on motor symptoms, cognition, and quality of life.

MATERIALS AND METHODS

We studied 22 patients (ten with FF-DBS and 12 with STN-DBS). Motor symptoms, cognition, quality of life, and gait symptoms were assessed using the motor part of the Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS III), the Mattis Dementia Rating Scale, the 39-item PD quality of life (PDQ-39), and the FOG questionnaire (FOG score) respectively. The levodopa equivalent daily dose was recorded. Comparisons of the FF and STN-DBS results were conducted.

RESULT

The mean follow-up was 6.18 years (95% CI: 5.57-6.78). Compared with the preoperative period, patients with FF had an average reduction of 32.2% in the MDS-UPDRS III scores (p < 0.01), a decrease of 35.3% in the FOG scores (p < 0.01), and an improvement of 25.9% in the PDQ-39 (p < 0.01). There was a 7.5% decrease in cognition (p < 0.01). Levodopa equivalent dose (LED) was reduced by 26.3% (p < 0.01). The STN group had an average reduction of 39.4% in the MDS-UPDRS III scores (p < 0.01), a decrease of 23.7% in the FOG scores (p < 0.01), and an improvement of 33.2% in the PDQ-39 scores (p < 0.01). Cognition decreased by 1.6% (p < 0.01) and LED by 15.06% (p = 0.02). Patients with FF-DBS were older than those with STN-DBS at the time of surgery: 61.2 years and 55.7 years, respectively (p = 0.02), and had longer duration of disease (p = 0.02). Patients with FF-DBS had a greater reduction in FOG (p = 0.02) than did the STN group and presented with a greater decrease in cognition (p < 0.01) after five years. STN-DBS had a greater effect on quality of life.

CONCLUSIONS

Both FF-DBS and STN-DBS relieved motor symptoms and improved quality of life over a long-term period. Patients with FF-DBS had a higher reduction in both FOG and in LED than did those with STN-DBS. These data support our hypothesis that FF-DBS is a safe and efficient option for treating motor symptoms in PD, including FOG in advanced stages.